Desk Light Transformer

I have a fluorescent desk light which houses a small transformer with
the prongs and plugs into the wall. The original plastic shell/cover
broke and rendered the light unusable. I believe it broke due to the
brittleness caused by the heat from years of use. Anyway, I like this
light and decided to make another cover out of wood which came out
pretty good. My only concern is that heat again. I drilled little holes
to help vent it but it's still a concern. I used a small piece of black
walnut I had laying around to make the shell. I used my thermal imaging
device (Flir adapter for phone) to read the temp of the unit which
reached over 100 degrees. Therefore, I'm wondering if this would be too
hot for the wood and can it cause a fire?

Wood starts to char at about 220F. Dry wood won't ignite until closer
to 400F.
But, I'm not sure how much cooler (than charring) you can safely operate.
I think even at ~200F for long enough time you'll see some discoloration
of the wood. Whether/when that poses a fire risk would be hard to say...
Note that you also have to consider what happens if the transformer fails
or degrades, over time.

you could add a thermal fuse to open the circuit if the temperature exceeds the combustion temp of the wood. this also protects from malfunction overheating.
why not convert to a LED bulb/s nearly zero heat that way:)

I'd be more interested in replacing the xformer with something like
a "brick" salvaged from an LCD monitor or laptop. You know it's
ratings (power) and know that it's been designed in a package
that can handle those limits...
But, that means knowing the output characteristics of the old xformer

Agreed. I've upgraded my entire house to LED but I have a problem with
throwing something away if it can still be used or still serves a good
function. My mindset is if I can repair, why buy anew. I like the
articulating features of the lamp due to it's reach. If I can replace
the bulb to LED, I'll go that route.

Good info. Thank you
The failing suggestions leads me to think that's what may be happening.
Because it become hot when I plugged it in, I unplugged it when I'm not
here. Before posting this question, I plugged it in again and felt it
after a few minutes. It's cool to the touch. Not even warm. Therefore, I
left it overnight and as I type, it's still cool. What the hell?

Even without a "load", a transformer "consumes power" in the form of
eddy currents in the laminations (of the core).
You may, also, have a failing transformer (winding that is shorting
out due to a failure of its insulation).
Or, a failure in the "load" that is causing a persistent (or intermittent)
additional burden on the transformer.
[Note that the transformer is undoubtedly sized JUST BIG ENOUGH to handle
the expected load. If that load is changing, then it is possible that
the transformer is being overtaxed and getting warmer]
If possible, I'd look at the transformer to see it's rated secondary
voltage (is it a transformer for an incandescent lamp? or, a *ballast*
for a fluorescent one??!) as well as its power rating (may be present
on a nameplate, somewhere).
If possible, consider replacing it -- even at the inconvenience of
having to rewire the lamp -- with an external transformer. I've done this
with one of the 12V halogen fixtures, here. And, I'm currently looking
for a suitable "power supply" that I can modify (variable output/"dimmer")
for an "illuminator" (columnar light source) that I use with my
stereomicroscope. Easier than trying to find the original (old!) device.

Yes. Some folks jump to conclusions -- without having (or trying to
ascertain) the facts, first!
There are fluorescent lamps in every LCD monitor. And, a ballast *in* the
monitor. Yet, all ALSO have a power supply -- either internally ALONGSIDE
the ballast/inverter *or* in an external brick. The fact that the
transformer was *in* the "PLUG" makes it even more likely that there
was a separate ballast elsewhere in the light. Otherwise, you'd be
pushing several hundred volts up the POWER CORD into the light (with
*more* than two conductors).
The OP could have clarified this EXPLICIT question. Villabozo apparently
thinks he can read minds and see through walls and across large distances.
Legend in his own mind.

No idea what goes on in his little mind. I don't see his posts
(filters, here) so wouldn't have known about it without seeing your
reply.
<shrug>
Sad when people don't think about whether or not their conclusions
"make sense" -- even given limited information available in a post.
"Let's see... if THIS is true, then all these OTHER things
would implicitly follow. (high voltage in power cord, more than
two conductors -- possible... but probable??) Do they ALL make
sense? Are they all LIKELY? Esp given the price and safety
pressures applicable to the item??"

I suspect there is a problem in the inverter *in* the lamp
("electronic ballast") that may be intermittent. So, the
wall wart sees a higher load and gets warm.
Hard to tell from the 2-terminal device in the photo
(black, one lead in a "curl") but that may be a temperature
operated cutout. Or, a PTC device (resettable fuse)

I had a fluorescent tube with a non-electronic ballast which would cause my UPS (which also runs the house lighting to make bulbs last longer) to hum loudly. Not sure what was wrong, but I traced it to the capacitor.

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